This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This is a cross-sectional comparison of insulin sensitivity, insulin secretion, and pancreatic B-cell compensation in siblings of women with and without GDM to test whether pancreatic B-cell compensation for insulin resistance is reduced in the siblings of women with GDM.